In general, facsimiles are connected to a public switched telephone network (PSTN) and can transmit and receive document data to and from other facsimiles connected to the PSTN and output the received document data.
Since facsimiles are connected to a PSTN, anybody can transmit fax data to the facsimiles if they know the fax numbers of the facsimiles. Accordingly, facsimiles may receive unnecessary data such as advertisements. In addition, the importance of information in a modern society increases, whereas a security device for data that is transmitted and received via facsimiles is weak.
There remains a demand for technology capable of reinforcing the security for a facsimile by filtering calling numbers and/or called numbers in transmission and reception of data via facsimiles and performing an authentication procedure on fax data for receiving an approval from an approver during transmission of the fax data.
In other words, if a facsimile has a function of blocking fax data from being transmitted with a specific called number, it can be considered that a security device for receiving places that receive the fax data is prepared to some degree. However, a special security device for the contents of fax data is needed. For example, if a company sets a transmission of fax data to rival companies to be blocked, the company is unable to transmit information about the company to the rival companies. However, as for confidential documents of the company, transmission thereof to every company via facsimiles need to be blocked. Therefore, a security device for the contents of fax data as well as for called numbers is needed.